These structures traditionally comprise a facing, a backfill behind the facing, stabilization elements distributed within the backfill to provide mechanical stabilization, and a system to connect the stabilization elements and the facing.
The facing is made, for example, from prefabricated concrete elements in the form of slabs or blocks, said prefabricated elements being placed side by side to cover the front face of the structure. A structure created in this manner is known by the commercial name TerraClass®, from the company TERRE ARMEE INTERNATIONALE.
The facing can also be made of a grid, particularly consisting of metal rods welded together. Such a facing can include a geotextile and can be revegetated. A structure created in this manner is known by the commercial name TerraTrel®, from the company TERRE ARMEE INTERNATIONALE.
Various types of stabilization elements can be used in such reinforced earth structures.
Certain structures include metal stabilization elements comprising bars of galvanized steel. It is also possible to use stabilization elements such as stabilization bands made of synthetic material, for example based on polymer fibers.
The stabilization elements are placed in the earth at a density that depends on the forces which may be exerted on the structure, with the thrust from the earth absorbed by the friction between the soil/stabilization elements. The stabilization elements are attached to the facing and/or to a wall separated from the facing.
Here we are concerned with metal stabilization elements.
Metal stabilization elements are often considered advantageous in terms of mechanical efficiency, and can consist of metal bars welded together to form, for example, a ladder or mesh. A ladder-shaped stabilization element generally consists of two substantially parallel metal rods, each constituting a longitudinal portion, and crossbars which connect the longitudinal rods together to give rigidity to the assembly.
A stabilization element resembling a ladder is formed in this manner.
In general, one end of the stabilization element comprises a means of attachment to the facing.
In the embodiment illustrated in FIG. 55 of U.S. Pat. No. 5,807,030, the two ends of the longitudinal rods are connected by a flat, pierced part. The pierced portion of said part is intended for receiving the means of attachment to the facing.
This solution offers numerous advantages, including a single connection point which allows forcing the stabilization element to deviate from the perpendicular at the facing and balancing the stresses between the two longitudinal rods.
However, such a ladder is obtained by welding, to the two longitudinal rods, the flat part intended to receive the means of attachment to the facing. This manufacturing process is long and costly.
Other solutions have been described, particularly the use of a “hairpin”-shaped ladder such as, for example, the one described in FIG. 38 U.S. Pat. No. 5,807,030.
These hairpin ladders have the advantage of being composed of only one longitudinal rod bent into a hairpin shape, thus decreasing the mechanical weaknesses at the link to the facing.
However, this type of ladder is not compatible with the conventional connections used in facings.
In addition, when this type of ladder is connected to the facing using a bolt or a pin, there is some longitudinal play remaining. This longitudinal play can result in different stresses in the various ladders connected to the same facing element and can affect the safety and/or cost of these elements.